Green’s Dictionary of Slang

akimbo adj.

[SE arms akimbo, standing with one’s hands on hips, elbows pointed outwards; ult. kimbaw v., thus note Grose, 1785: ‘a kimbaw, vulgarly pronounced a kimbo [...] an insolent bullying attitude’]

(UK society) arrogant, stand-offish.

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I. Brown Just Another Word 24: ‘She got terribly akimbo’ became a species of Mayfair slang for what was earlier called ‘high horse’. I have also heard it used by stage people for over-acting. ‘So and so was a bit akimbo to-night.’.